In accordance with the recent trend of an aging society, a coronary artery disease such as angina pectoris, myocardial infarction, or the like, has increased at a rapid rate in adults in Korea over the last 10 years, and is the highest cause of death except for cancer. The coronary artery disease is a disease that occurs in blood vessels surrounding the heart, and causes blood supply disorder in the heart muscle. The most common cause of the coronary artery disease is arteriosclerosis. When plaque made by a combination of cholesterol and other fats accumulate in coronary arteries, and various other components in blood are correspondingly increased, which cause coronary stenosis, and accordingly, blood supply to the heart muscle is reduced, which results in lack of nutrients and oxygen. As a result, it may cause chest pain (angina) or myocardial infarction, and even worse, lead to death.
Therefore, as a method of treating the diseases occurring in the blood vessels, a treatment method of expanding blood vessel passages narrowed due to stenosis by using an implantation tool called a stent has been generally and frequently used.
When stenosis or occlusion occurs in vascular or nonvascular lumen in a human body, the stent is a general term for medical devices for the purpose of opening the lumen. The stent was first suggested by Charles R. Stent at the end of the 19th Century, while stent implantation was first attempted in the peripheral artery by Charles Dotter in 1969, and a stent having a single spiral structure was invented by Maass in the 1980s.
The stent placement surgery using the stent is most common in terms of most treatment methods for a cardiovascular disease due to a low restenosis effect and a previously proven treatment effect, and usage frequency and reliability of the stent have continuously increased. In addition, recently, research into localization of a drug-eluting stent (DES) in the country has also been actively ongoing.
The drug-eluting stent (DES) in which a drug is directly delivered to a cell or a tissue by coating the drug on a surface of the stent so as to reduce restenosis in the stent was developed and usage thereof has been gradually increased.
However, after the stent placement surgery, damage occurs in the blood vessel which induce proliferation of smooth muscle cells according to an immune response to the stent at an initial induction, and problems such as in-stent restenosis (IRS) by smooth muscle cells proliferated in the blood vessels and acute thrombosis, late thrombosis, inflammation by a polymer used in coating, and the like occur.
Although a number of researches for solving the above-described problems have been conducted, most of them are to use drug coating technology for standardized drug controlled release capable of preventing restenosis, or is on the basis of inhibition of restenosis, and are limited to develop a drug coated stent simply controlling a drug in a continuous way rather than a coating technology for controlling a drug release according to a vascular therapy mechanism. Drugs currently used for commercially available DES are sirolimus or -limus family drugs that are a substitute for sirolimus, which are effective for inhibiting restenosis, but do not solve problems caused by DES usage, which is not sufficient in inhibiting inflammation, promoting re-endothelialization, inhibiting late thrombosis, and the like.